This invention relates to a gas generator, in particular a tubular gas generator for an air bag, with a housing for accepting a gas-producing material and at least one safety self-ignition device for igniting the gas-producing material at a predetermined minimum temperature of the housing which is secured to the housing in a particularly effective heat-conducting manner.
A gas generator containing self-igniting material is disclosed in DE-39 14 690 C2. The housing of this gas generator consists of two tubes (outer and inner tube), fitted into one another, which are radially spaced from one another. The outer tube is closed in a gas-tight manner on its front ends by substantially disc-shaped closure covers. The inner tube surrounds a gas-producing material (pressure gas-generating charge), which is ignited by an electric ignition device. The electric ignition device is secured to one of the two closure covers. The ignition device is provided with an ignition charge, which is ignited electrically and ignites, for its part, the gas-producing material. The ignition charge is admixed and is a self-igniting material, which ignites when reaching a certain minimum temperature. This minimum temperature lies well below the self-igniting temperature of the pressure gas-generating charge. The self-igniting material has the function of a thermal safety means for the gas generator. In the event of a fire (for example a vehicle fire) or in the event of a fire during storage and transport of the tubular gas generator, this is heated. With the heating, the mechanical properties of the housing deteriorate, said housing no longer having the pressure stability required against bursting apart with high temperatures. Because of the heating of the housing (tubes and closure covers) the ignition device also warms up and the self-igniting material, accommodated therein ignites the gas-producing material when reaching its self-igniting temperature, at which the mechanical properties of the housing are still sufficiently good. The entire housing of the known gas generator consists of aluminum. Aluminum has a relatively high thermal conductivity. Because of this high thermal conductivity there is the danger that the gas-producing material greatly heats via the gas generator housing, so that when igniting such a strong gas formation occurs that the housing bursts.